1. Field of the Invention
This invention relates to a spliced non-directional belt which is particularly adapted for use in the heat sealing and plastic film wrapping packaging industry.
2. Description of the Prior Art
Packaging and conveyor belts are used in a wide variety of applications. One area in which such belts formed from polytetrafluoroethylene (PTFE) coated glass fabrics are used is in the packaging industry. In particular, apparatus is in wide use today which is known as form-fill-seal packaging equipment. In such equipment, a web of flexible packaging material, typically a plastic film, is pulled from a supply and is fed over a device for forming it into a tube, a product to be packaged is then provided in the tubing, the tubing is separated into individual packages, the ends of the packages may be folded over and are sealed. Examples of products which are packaged in such manner are cylindrical paper rolls which have hollow cores. These rolls, such as toilet paper or paper towel rolls, are typically packaged in a plastic film in a compressed state to facilitate shipping.
One type of equipment that is used in such application is made by the Hayssen Manufacturing Company of Sheboygan, Wis. USA. Such equipment uses packaging belts to transport the product and heat seal a plastic wrap around the product. In the latter operation, in one equipment design the packaging belts are typically positioned vertically and surround heat seal bars which are used to heat seal the ends of the package. PTFE coated glass fabric endless belts are used in such equipment since the belts are strong, resistant to heat and do not stick to the plastic film. Typically these belts are fairly narrow, having a width on the order of about 4 to 15 inches (about 102 to 381 mm) and a length on the order of 8 to 18 feet (about 2.03 to 4.57 m). These belts may be provided with fastening studs or other guiding means along one or both edges which are adapted to operate with pulley wheels on the equipment.
Such endless belts have been heretofore fabricated with overlapping angled splices (typically angled at 45 degrees). These splices are either right-handed or left-handed, depending on the intended direction of rotation of the belt. That is, the angled end of the belt that overlaps the other angled end is intended to face away from the direction of rotation of the belt so that this end does not get caught up in the equipment and cause damage to the belt.
One of the problems associated with this existing system is the need to manufacture, order, stock and install belts of both the right-handed and left-handed variety, depending on whether the belts are intended for rotation in the clockwise or counterclockwise direction when installed in the machinery. Through carelessness or lack of knowledge, end users frequently inadvertently install the wrong rotation belt causing premature belt failure. The edges of these splices delaminate and may cause the belt to self destruct. This is costly both in terms of belt replacement, equipment down-time and dual stock requirements.
In the existing belts, the splice also has a tendency to wick chemicals that are applied to the belt. In some packaging equipment, liquid release agents, lubricants or other chemicals are sprayed onto the belt so as to ensure that the belt does not stick to the plastic film that is used as the package overwrap. Wicking or pickup of such materials can cause premature delamination of the splice and/or fraying of the glass fabric.
It would be desirable to provide a spliced belt which is non-directional, such that the belt could be used in either direction of rotation. It would also be desirable to provide a spliced belt which alleviated the other problems discussed above.